


Under my Skin

by overdose



Category: Fate/Zero, Fate/stay night & Related Fandoms
Genre: Anal Sex, Blow Jobs, Child Gilgamesh (Fate), Church Sex, M/M, Shotacon, Underage Sex
Language: English
Status: Completed
Published: 2020-03-15
Updated: 2020-03-15
Packaged: 2021-02-28 20:14:48
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 1,838
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23153089
Author URL: https://archiveofourown.org/users/overdose/pseuds/overdose
Summary: A young Gil taunts Kirei.
Relationships: Gilgamesh | Archer/Kotomine Kirei, Kid Gil | Archer/Kotomine Kirei
Comments: 3
Kudos: 44





	Under my Skin

**Author's Note:**

> My first Gilgamesh and Fate fic is shotacon. I don't know why I'm like this.
> 
> And yes I grailed kid gil to level 80 in fgo.

Kirei recognized the childish laughter approaching him from behind. He sighed and sank down into the edge of a pew, watching a young version of Gilgamesh skip toward him. 

"Evening, mister," Gil said with a flashing smile. "It's soooo boring down here," he frowned and looked around the dark, empty church. "Can we do something fun?"

"How about tomorrow?" Kirei offered. "I'm tired." 

"Silly Kirei," the child giggled. "If you want, you don't have to do anything. Just sit back and watch," he took a step forward and placed a hand on Kirei's legs. "Those books you have in the library really fuel a child's imagination~" 

"Gil," Kirei scolded. He knew he would play right into the kid's hand. No matter what form he was in, Gilgamesh found a way to get what he wanted. "What do you have in mind?"

Gil said nothing but giggle again as he crawled on Kirei's lap. 

Kirei stopped him immediately with a harsh grasp to his sides. Gil squirmed and let out a pained cry. "Enough, Gilgamesh. Surely you're not thinking of doing that to a man of God, especially in a church." he softened his grip and watched Gil stumble back.

"Meanie," Gil stuck his tongue out. "And you're far from a man of God, you know!”

"Need I remind you that you're a child? Come back to me when your youth potion runs out." Kirei crossed his arms and ignored Gil’s pout. He knew that wouldn’t stop anything.

Gil, despite being a youthful, kind boy, was still Gilgamesh. “I don’t wanna,” he said. “‘Cause I like you, Mister Kirei. I know what adults do when they like each other.” Gil took quick, small steps towards Kirei again and reached for his rosary. “Oopsie~”

The rosary snapped in the boy’s arms when he pulled it. Gil tilted his head with a smile and found himself back on Kirei’s hips. The priest wore a scowl and gripped Gil’s tiny body, though Gil didn’t mind as he leaned in to kiss the older man. Kirei had more than enough strength and the authority to stop him, but a sick curiosity prevented him from doing so. He led his hands down Gil’s body and grasped his rear. Gil surprisingly knew how to kiss well despite his age, grinding on Kirei and using his small tongue to the best of his ability. Muffled whimpers left his lips while he cupped Kirei’s cheeks, desperately seeking friction between their clothed bodies. 

“Hah... I knew it...” Gil looked down at Kirei’s lap as he pulled away, panting. “Already...? How unholy of you, priest…”

Kirei wiped Gi’s drool away from his lips. “What did you expect? With you moving against me like that, of course I would get an erection...” he tried to play it off like nothing, but deep down he knew he was a sick pervert who enjoyed the young Gilgamesh touching him.

“Haha, well… I suppose I’ll have to help you now, right?” Gil left Kirei’s lap and dropped to his knees. He didn’t wait for Kirei’s response because the priest didn’t do anything but sit back and wait. Gil chuckled with amusement and wasted no time in taking Kirei’s hard cock out. He locked eyes with Kirei as he put it into his mouth and waited to see any type of emotions, whether it be guilt or satisfaction. 

Gil used his small hands to touch his shaft while he eagerly went down on him, red eyes taunting. The girth of his cock was far bigger than Gil’s skinny arms and he wondered how the boy didn’t gag or choke.

“God… what am I doing?” Kirei stared at the ceiling and asked aloud. “To sin like this…!” his fists curled, body going against his mind when he moaned, inviting Gil to go further. Kirei shut his eyes and forced himself to think of anything but the child in front of him. It didn’t work. He wanted Gil’s pink lips on his cock, his small mouth struggling to take it all, and he shivered to think how his cock would fit inside him.

No, I can’t allow this to go on further, Kirei thought. “Gil, I think that’s enough…!” he said, his hips automatically jerking to the pleasure Gil brought. 

The young Archer didn’t stop and wasn’t planning on doing so no matter what Kirei said or did. 

Kirei cursed and grasped Gil’s blond hair, forcing him up. “I said enough,” he growled. “You damn brat.”

Gil came up with a gasp. As he caught his breath, he laughed. “Oooh, scary,” he said. “Make me stop, then… but do you really want that?”

He knows everything… What's the point of stopping?

With a gulp, Kirei calmed himself down and forced Gil back on him. He groaned and knew he had to finish soon. Gil’s red eyes widened with tears, but he continued to take Kirei’s cock even if it made him cry and drool everywhere. His throat hurt as Kirei fucked his throat with erratic thrusts. 

“This is what you wanted, Gilgamesh,” Kirei taunted and gripped Gil’s hair, forcing him to stay in place. “Now, be a good boy and take my seed.”

Gil couldn’t respond with a snarky remark. Soon after Kirei’s words, his throat filled up with the priest's cum, taking the bitter, salty taste that made him wince. Kirei finally let go of his head and allowed him to get fresh air, letting out a satisfied sigh.

“M-Meanie…” Gil coughed, his voice hoarse from the length he had to take.

He looked like a mess with his dirtied lips. Kirei enjoyed the sight. “You brought this onto yourself,” he said and stood up. “However, don’t think I’ve finished with you.”

“H-Huh?!”

Kirei lifted Gil by his white hoodie and threw him onto the pew. A small item fell out of his pocket, and Kirei reached for it. He chuckled in disbelief. Gil carried lube with him. “You came prepared, you brat.”

“Ah… Yes, I did. Hehe~” Gil adjusted himself in a comfortable position on the pew. He removed his hoodie and tossed it aside, pulling down his shorts and underwear afterward. “It was hard to get them since I’m so young.”

“It’d be a waste if we didn’t use it, then,” Kirei said and grasped Gil’s bottom. His touch was chilling, evident from Gil’s shiver. He grinned and popped open the bottle of lube. While he never had sex with a man (a boy, a child), he knew what to do. Kirei coated Gil's hole and around it with lube, then his fingers, wasting no time in pushing one in. Gil tensed up with a whimper. “Enough of that. I just started.”

“Sorry…” Gil apologized.

“Good boy.” 

Kirei had passed the point of forgiveness. He waited for Gil to calm down before he pushed his finger further in, and as he added the other in, he let out a scoff. What was the point in preparing him? His fingers weren’t enough for Gil to get used to his length. 

He needed to teach Gil a lesson, too.

Removing his fingers, Kirei grabbed the lube again.

Gil turned his head back with a frown. The wooden surface underneath him hurt his knees and arms. “Hey, mister, that’s not enough!”

“I know,” Kirei replied as he jerked his cock off, applying lube at the same time. Once he got hard again, he neared Gilgamesh and grabbed his ass, spreading his bare cheeks. “It’s fine, Gil. You can handle it, right?”

“Nuh-uh!” Gil complained. “H-Hey, Mr. Kirei…” he felt the tip of Kirei’s cock teasing his hole, moving closer with every second. “It...It…” hurts, feels good, Gil didn’t know what to say, and Kirei didn’t care either way, slamming his cock into the young boy seconds later.

Gil cried out and slammed the pew. “Kirei!” he curled his fists and watched drool dribble down the wood while his body jerked with each thrust. Knowing Kirei, he should have figured out the man would take matters into his own hand. “Owie! You mean priest!”

“This is fitting for a priest, isn’t it?” Kirei mocked. “But you’re not backing out now, are you?” he asked with a groan. Gil’s tightness felt better than he thought it would.

“No…” Gil replied with a shaky voice. “Keep going, please,” he begged. “Pretty please!”

Kirei grunted and kept moving his cock in and out of Gil. He maintained a firm grip on the boy and knew he made a few marks due to his strength. How his cock stretched out Gil made his stomach twist into knots, but he couldn’t stop fucking the boy, gaping his hole.

“God, how delightful…” Kirei commented. Gil’s squeaky moans turned him on even more, and he sped up, pushing his cock further in. The church, rather than prayers or hymns, harbored a man committing one of the worst sins possible. So, this is pleasure Gilgamesh talked of, he thought.

Gil twitched under him and started moaning incoherently. “M-More, Kirei~ More, please, I w-want - more!” he whimpered, hoping the priest would hear him over the smacking. “Fuck,” the boy sobbed. “I’m close!”

“Ah,” Kirei said mid-thrust. “I forgot you were a child… they tend to finish fast if they’re able to.”

Gil tried to frown but his lips quivered into a sob. Kirei slammed his cock yet again and didn’t even know he was abusing Gil’s prostate. He clawed the seat with his nails and made a dent that Kirei didn’t notice. His body shivered but he couldn’t collapse or lay down. Kirei had a strong grip which he refused to let go of. Tears fell down Gil’s cheeks before his body shuddered. His small cock let out tiny spurts of cum on the pew as he mumbled Kirei’s name with a hazy mind.

Kirei felt the boy’s convulsion and decided to fuck him harder, faster, trying to meet his end, too. He paused and didn’t shy from being loud. His groan echoed in the church, forever within the walls to haunt him later. Finishing inside Gil, Kirei watched his cum ooze out of his hole even before he pulled out. It was shameful to think that orgasm was one of the best he ever had, but it was. 

He wanted more.

Gil whined again and finally let his body rest on the seat. He couldn’t get up. “Kirei…”

“Yes, boy?” Kirei replied while fixing his clothes. 

“I’m hungry. What’s for dinner?”

"Fix yourself first, and I'll come up with something."

"But you fucked me too hard," Gil frowned. "I'm super worn out. You do it." 

The priest sighed. He sat next to Gil and put his shorts back on, retrieving his hoodie after. Gil still had cum in him and dripping down his legs. "Ugh," Kirei felt a headache coming. "Punishment for my sin, I suppose."

"Hehe, who's fault is that?"

Kirei lifted Gil in his arms and carried him. "I don't want to hear it, Gilgamesh," he said, holding back an amused grin.


End file.
